Structural insights into the Oryza sativa cation transporters HKTs in salt tolerance

ABSTRACT The high‐affinity potassium transporters (HKTs), selectively permeable to either Na + alone or Na + /K + , play pivotal roles in maintaining plant Na + /K + homeostasis. Although their involvement in salt tolerance is widely reported, the molecular underpinnings of Oryza sativa HKTs remain elusive. In this study, we elucidate the structures of OsHKT1;1 and OsHKT2;1, representing two distinct classes of rice HKTs. The dimeric assembled OsHKTs can be structurally divided into four domains. At the dimer interface, a half‐helix or a loop in the third domain is coordinated by the C‐terminal region of the opposite subunit. Additionally, we present the structures of OsHKT1;5 salt‐tolerant and salt‐sensitive variants, a key quantitative trait locus associated with salt tolerance. The salt‐tolerant variant of OsHKT1;5 exhibits enhanced Na + transport capability and displays a more flexible conformation. These findings shed light on the molecular basis of rice HKTs and provide insights into their role in salt tolerance.